Process for the manufacture of plasticcoated tubular articles

ABSTRACT

Method of continuously applying a plastic coating to a tubular article normally one which is not self-supporting. The said tubular article in flattened condition is passed over a ball means which coats with extrusion inlet to restore the flattened article into cylindrical configuration for coating of said tubular article. The plastic is formed as an annular stream into which the article is passed.

F 5, 1914 s. M. MEMGE'R 3,790,651

PROCESS FOR THE MANUFACTURE OF PLASTIC-COATED TUBULAR ARTICLES OriginalFiled Jan. 18, 1967 2 Sheets-Sheet 1 INVENTOR SYLVESTER 'MEITINGERATTORNEY Feb. 5, 1974 s. M. MEITINGER 3,790,651 PROCESS FOR THEMANUFACTURE OF PLASTIC-COATED TUBULAR ARTICLES Original Filed Jan. 18,1967 2 Sheets-Sheet 2 /////V/// \\\\\I\\\\k\\\\ 74 l l H J I I I I l IINVENTOR SYLVESTER M. MEITINGER BY w W A9 q rl' ATTORNEY 3,790,651PROCESS FOR THE MANUFACTURE OF PLASTIC- COATED TUBULAR ARTICLESSylvester Marfin Meitinger, Toledo, Ohio, assignor to Stautfer ChemicalCompany, New York, N.Y. Continuation of abandoned application Ser. No.862,102, July 7, 1969, which is a division of application Ser. No.610,095, Jan. 18, 1967, now Patent No. 3,533,133, dated Oct. 13, 1970.This application Aug. 5, 1971, Ser. No. 169,499

Int. Cl. B2911 23/05 US. Cl. 264-135 4 Claims ABSTRACT OF THE DISCLOSUREMethod of continuously applying a plastic coating to a tubular article,normally one which is not self-supporting. The said tubular article inflattened condition is passed over a ball means which coacts with anextrusion inlet to restore the flattened article into cylindricalconfiguration for coating of said tubular article. The plastic is formedas an annular stream into which the article is passed.

This application is a streamlined continuation of application Ser. No.862,102, filed July 7, 1969 and now abandoned, which latter applicationwas a division of application Ser. No. 610,095, filed Jan. 18, 1967, nowUS. Pat. No. 3,533,133, issued Oct. 13, 1970.

This invention relates to a process for applying a plastic coating to atubular substrate.

The term plastic as used herein includes natural and synthetic resinsand elastomers; also other materials which are capable of being extrudedthrough a die or similar instrumentality. In most instances, the plasticmaterial is required to be cured or set following application of thesame to the substrate The invention is especially applicable where thetubular article coated or covered is of a fibrous nature. Such a tube ismost frequently of braided construction, but may be knitted, woven oreven felted. The fibrous material may be of mineral derivation as glassor asbestos, for example, or it may be of animal or vegetable origin,e.g., wool, cotton, ramie, etc. Additionally, synthetic fibrous orfilamented materials, such as nylon and rayon, have application to theinvention.

In general, it is contemplated that the tubular article subjected to thecoating operation is so flexible and supple as not to beself-supporting.

Heretofore, plastic coatings have been applied to fibrous tubing orsleeving using a clipping process. Such process is extremelytime-consuming, particularly in that repeated dippings are usuallyrequired in order to build up a coating of the proper thickness. Apartfrom this, it is ditficult to satisfactorily control the cross-sectionalshape of the coated tube and to achieve a coating of uniform thickness.

The present invention has as its principal object to provide a methodwhereby the fibrous or other tubing is uniformly coated in a speedy,continuous manner.

Another object is a system which is subject to substantially completeautomation.

Still other objects and features of the invention will be apparent fromthe following description of a preferred embodiment thereof. Thedescription will proceed with reference to the accompanying drawingswherein FIG. 1 diagrammatically illustrates the over-all system;

FIG. 2 shows in section a die assembly used in the system;

FIG. 3 is a view on the line 33 in FIG. 2; and

FIGS. 4 and 5 are sectional details, FIG. 5 being a modification.

United States Patent 3,790,651 Patented Feb. 5, 1974 Referring first toFIG. 1, it will be seen that the tubing or sleeving 10 to be coated isderived from a reel 12. The tubing is drawn, respectively, through aprimary bath 14, a squeeze block 16 and an oven 18 by a capstan 20. Fromthe reel 12, the tubing 10 will be observed as passing about an idler22, thence under an idler 24 in the bath 14 and, thereafter, over anidler 25 into the squeeze block 16.

A ball 26 disposed within the tubing and having a diameter greater thanthe passageway through the block 16 coacts with an abutment 27 providedby said block to remove primer solution from the tubing. The removedsolution is caught by receptacle 30 which communicates via a pipe 32with the vessel 14.

The oven or evaporator 18 is maintained at a temperature such thatessentially the last vestige of solvent is removed from the tubing.

Upon leaving the oven, the dry, primed tubing is sequentially passedthrough a die assembly 34 and a curing oven 36. Powered reel 38 isoperated in timed relation with respect to the capstan 20, so that thetension on the tubing is substantially constant.

' A second ball 40 within the primed tubing 10 coacts with an abutment42 forming part of die assembly 34 to restore the tubing to cylindricalform, the same having been flattened incident to its passage through thecapstan 20.

Going now to FIG. 2 of the drawing, it will be observed that the dieassembly 34 comprises a generally cylindrical housing or casing 44.Centered 'within this housing member is an adapter 46 having anintegeral an nular flange 48 whereby it is locked to the housing memberby means of a nut 50. Such nut has a flange 52, which will be seen asabutting the flange 48.

Rightward of the adapter 46 is disposed the body portion 54 of a dieelement 55 which further includes a tapered, hollow boss 56 and anelongated tubular portion 58. It is the tubular portion 58 of the dieelement which provides the abutment 42 coacting with the ball 40 torestore the primed tubing 10 to a cylindrical form.

Upward of the casing 44 and secured thereto by means of a clamp collar60 is a feed screw assembly 62. As shown, the casing of such assembly isformed to provide a passage 64 for the circulation of coolant or heatingfluid, when needed. The thread 68 of screw 66 is desirably formed with areduced pitch at the lower end of the screw to the end of attaining acompressive effect. Screen 70 serves to prevent the entry into the dieassembly of any lumps which may be contained in the plastic feed stock.

Housing 44 is to be seen as having a tapered bore 72 receiving plasticfrom the screw assembly. The bore 72 communicates with a groove 74 cutin the wall of the adapter 46. This groove (74) communicates with aperipheral port 76 (FIG. 3) in the body portion 54 of the die element 55via radial groove 78 located in the left face of such portion 54.

The body portion 54 of the die element 55 nests within an adapter 82located by a plug 84 held in place by a nut 86 threaded into the housing44.

From FIG. 3, it will be noted that the right face of the body portion 54of the die element 55 is channeled to the end that the stream of plasticentering through the port 76 is divided and subdivided to an extent suchthat the annular groove 88 surrounding the boss 56 is served by no lessthan eight passages 90. This assures that the annular groove 88 will atall times be completely and uniformly filled with the plastic beingapplied to the tubing 10.

The arcuate channels in the die element 55 (FIG. 3) are closed by theadapter 82, which tightly abuts the right face of the portion 54.Annular groove 88, on the other hand, opens to an annular taperedpassage provided by the boss portion 56 of the die element 55 togetherwith the adapter 82 and the plug 84, which are supplied with registeringapertures tapered in a manner complementary to the tapering of the bossportion 56.

Aperture 91 (FIG. 3), not shown in FIG. 2, accomodates a pilot pincarried by the adapter 82 at the inner face thereof.

An annular recess 92 in plug 84 is for the accommodation of an O-ring94. Such O-ring has a diameter, before installation, less than that ofthe primed tubing 10. Hence, it exerts a constrictive force on theplastic as it leaves the end of the annular or tubular passage. Theplastic material is thus firmly bonded to the primed tube 10 and wheresuch tube is formed of a fibrous or other material having interstices, aportion of the plastic becomes embedded in the body of the tubing asillustrated by FIG. 4 in which the numerals employed correspond to thoseused to denote like parts in FIG. 2.

In the modification of FIG. 5 wherein similar numerals are employed,these, however, being primed, the plug 84 in lieu of an O-ring has anannular land 96 formed internally thereof to provide the constrictiveefl'ect securing the bond between the plastic and tubing.

Although the operation of the die assembly (FIG. 2) is surely apparentfrom the foregoing, a brief summary thereof may be in order. As beforestated, the ball 40, which is advantageously formed of Teflon, functionswith the abutment 42 to restore the primed tube to its cylindrical form.As the tube travels through the tubular chamber delineated by the dieelement 55, the screw 66 forces the plastic material through the screen70, thence through the passages 72, 74 and 78 into and through theclosed die channels (FIG. 3). There is thus produced a tubular stream ofplastic corresponding in initial diameter to that of the annular groove88. The speed at which the annular stream travels the tapered passageabout the boss 56 substantially corresponds to the rate of movement ofthe primed tube, which makes contact with the annular stream at a highlyacute angle just inward of the constricting O-ring.

Modifications other than the modification herein described may be made,of course, without departure from the invention, the scope of which isset by the accompanying claims.

The invention claimed is:

1. A method of applying a plastic material to a tubular article whichcomprises continuously drawing a flattened tubular article over a ballmeans which is internal to said tubular article and has a diametergreater than the inlet of an extrusion device and coacts with said inletto restore the flattened tubular article to a cylindrical configuration,drawing the tubular article through the extrusion device at asubstantially constant predetermined rate without any internal supportwithin said extrusion device, continuously introducing a single streamof the plastic material into said device at a rate synchronized withrespect to the rate of introduction of the tubular article thereinto,subdividing said stream within said device into two streams and furthersubdividing said streams into a plurality of streams, converting saidplurality of streams into a single tubular stream moving in thedirection of said tubular article and enveloping the same, continuouslydepositing said tubular stream on and about said tubular article to forma coatingrthereon, said stream and said article forming an angle of lessthan between the direction of movement of the article and the tubularstream at their point of contact and subjecting the coated articlewithin said device to a radial constricting force operating to securethe bond between the plastic and the article.

2. The method of claim 1 wherein the tubular article is first treatedwith a primer solution, dried, and passed to the extrusion device in aflattened condition and thereafter being restored to a cylindrical formprior to being drawn through the extrusion device.

3. The method of claim 1 wherein the flexible tubular article is formedof a braided fibrous material and sufiicient constrictive force isapplied to the plastic coating to cause a portion of the plastic to beembedded in the body of the article.

4. The method of claim 1 wherein the tubular stream becomesprogressively reduced in diameter as it approaches its point of contactwith the said article.

References Cited UNITED STATES PATENTS 2,324,645 7/1943 Prehler 2641363,106,748 10/1963 Skobel 264173 3,159,877 12/1964 Orsini 425-1133,359,357 12/1967 Bentley, Jr. et al. 264-173 3,249,666 5/1966 French264174 3,183,135 5/ 1965 Berquist 264174 2,838,799 6/1958 Meister 264-ROBERT F. WHITE, Primary Examiner J. R. THURLOW, Assistant Examiner US.Cl. X.R.

